Intelligent mass flow controller
Patent 5062446 Issued on November 5, 1991. Estimated Expiration Date: 
January 7, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
January 7, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod for controllably positioning a solenoid plunger Computer aided tuning of turbine controls Air flow metering terminal and control system Diagnostic apparatus and method for fluid control valves Patent #: 4976144 InventorApplicationNo. 638279 filed on 01/07/1991US Classes:137/468, Thermal responsive137/486, Responsive to change in rate of fluid flow137/487.5Electrically actuated valveExaminersPrimary: Cohan, AlanAttorney, Agent or FirmInternational ClassG05D 007/06AbstractAn intelligent mass flow controller for controlling the mass flow of gas to a semiconductor processing chamber. A sensing circuit measures a difference in temperature across a sensing tube and translates this difference to adjust a valve for controlling the mass flow. A microcontroller which includes a CPU, signal processing and software routines continually monitors the various parameters and provide "on the fly" corrections, as well as providing diagnostics and record retention.Other References
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